


Jack and Jeannie

by ForbiddenArchive



Category: Fate/Apocrypha
Genre: ABDL, Adult baby, Breastfeeding, Diapers, F/F, Mental Regression, Soiling, Wetting, diaper lover
Language: English
Status: Completed
Published: 2019-05-26
Updated: 2019-05-26
Packaged: 2020-03-18 00:13:55
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 3,940
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18975121
Author URL: https://archiveofourown.org/users/ForbiddenArchive/pseuds/ForbiddenArchive
Summary: Ruler meets the wild card Assassin of Black during the nighttime fog. The encounter will leave her a changed girl... in a few different ways.





	Jack and Jeannie

The Great Holy Grail War. A once in a life time event where fourteen maguses and their familiars, mythical beings known as servants, do battle in teams of seven in an attempt to gain the favor of the Greater Grail that powers the whole ceremony. Red and Black, locked in a struggle kept in check by a single woman known as Ruler.  
  
Ruler, Jeanne D'Arc. The French saint. The overseer of the grail war. The one woman that arbitrated the entire event... and ultimately, the one that both sides wanted to sway the most, due to the powers that she held. With her on either of their sides, the war would be tipped in that side's favor...  
  
Maybe with this in mind, it would explain the rumors that had sprung up recently. Mist rolling in and filling the streets, seemingly consuming anybody that ended up inside of it. The only things left behind by the mist were the victims' clothing and a few droplets of blood. Only something like a Servant could cause an incident like this, that much was certain. Fog couldn't just appear out of nowhere with no prior warning or indication.  
  
All of this would explain why Ruler was currently taking small steps down the paved roads of the city, fully garbed in her armored dress, sword at her hip and flag in hand. If she happened to find the culprit behind the incidents, and they were a servant? She'd reprimand them and strip them of their chance to compete for their side. Effectively, she would make them a third party, an enemy of both teams... and thus, they would swiftly be eliminated.  
  
"I just hope this bloodshed will end with my intervention. I would prefer not to interfere in this war, more than necessary..." The blonde servant muttered to herself, only to freeze in place as she realized that she had already succeeded in locating the culprit... because said culprit suddenly bumped into her and caused them both to fall onto their bottoms, eliciting a soft cry of pain from the pair.  
  
"Owwie..." The girl sitting opposite of Jeanne muttered as she rubbed at her butt and started to pout. "Geez, Mommy, you're supposed to move when you see somebody coming..." The little girl said as she crossed her arms. She seemed comically upset about such a minor thing, but at the same time she didn't act on her mood...  
  
Jeanne on the other hand remained composed as she looked at the little girl, tilting her head ever slightly as she tried to piece together just what kind of servant the girl was. It didn't take too long before she figured it out however, knowing that only one type of servant would pull of a plan like this. "Assassin...?" The Ruler class servant asked aloud, as she slowly stood back up.  
  
"Mmhm! Black Assassin Jack, at Mommy's service!" The little albino girl said in a chipper manner once she got up as well, only to suddenly gasp audibly as she realized just who the blonde was. "Mommy's Ruler!" Jack blurted out as she began to giggle a little madly. "Good, good~ Mommy said to Jack that she should take extra care if Ruler showed up... so Jack's going to make sure that Ruler Mommy doesn't cause trouble for her Mommy!"  
  
It was a little hard to keep track of who the little girl was referring to, but the spiel was enough to make Jeanne certain that it was Assassin who had caused all the disappearances. Just as she was about to ready her flag for combat however, the girl had vanished by the time her eyes fell back upon her. In her place was a thick layer of fog, and the ethereal sound of the little girl giggling throughout the town. Needless to say, the little girl had managed to lure Jeanne into her trap, whether she had overtly intended to do so or not...  
  
"Look, Assas- I mean, Jack... It's not nice to do what you've been doing to people... You really should stop, listen to Mommy." Jeanne did her best to sound like a source of reason, but all that earned her was another couple of laughs from the girl hidden within the mists.   
  
"But Jack likes murder, Mommy! It makes her Mommy all happy, and that makes Jack happy!" The voice sounded like it had no true source, but the girl had to be hidden somewhere within the dense mists. From Jeanne's own understanding of the world, couple with what she knew about the Assassin she was facing, she could tell that the mists mimicked those that were found in London around the time of the murders that made Jack famous, so naturally the fog must've come from one of her skills...  
  
But there was something about the fog that unnerved the French saint. Something about the air that made her worry for her own well being. And she was right to, because the moment she let down her guard to wonder why the air felt this way, suddenly felt something strike at her side. It wasn't painful, more like she had been lightly brushed against, but it had to have been Jack's doing. Nobody else was around.  
  
"Come out, Jackie! Don't be mean and make Mommy do bad things to you!" The way Jeanne spoke had gotten rather childish, something she only noticed once she let the words bounce around in her noggin for a little bit. "W-Why's I speaking like this?!" The now-frightened saint shouted as she suddenly felt herself get shoved forward again, a light shiver coursing through her body as she tried to get her eyes on the Assassin that kept darting back-and-forth.  
  
Unfortunately, all her frantic searching led to no real result, besides the girl getting pushed more and more. With every push, she felt the core of her soul getting crowded. She didn't realize it, but every time Jack had bumped into her within the fog, she had managed to let one of the souls that served as the foundation of her being, jump into the other Servant's body. This not only served to make the Ruler weaker than she really was, but it also made her start acting more and more like a child, the more orphaned souls became a part of her...  
  
The blonde haired servant had begun to shake back and forth, as her heart started to waver, her soul getting awfully crowded in between all the other kids that had joined in on inhabiting her body. "Uuuu... Stoppit, Jackie, Mama don't like it when you're mean..." The formerly composed ruler muttered aloud as she tried to keep an eye out for the little girl, and yet still failing. It got to the point where Jeanne pulled her flag outward and just started swinging it wildly, like a child throwing a tantrum. She didn't know any better.  
  
Once the blonde saint looked as if she had managed to tire herself out, her breathing sounding ragged and almost whiny as she struggled to keep herself standing with the butt of her flagpole, she felt something push against her butt. Something a bit more intense than just a regular shove, in fact this one was powerful enough to make her topple over!  
  
Jeanne gasped as she hit the pavement, sniffling slightly as she had a bright red mark on her cheek where the flag had collided with her face. "Jaaackie..." She murmured with a little slur in her voice as tears began to well up in the corner of her eyes. She just couldn't keep her new childish habits in check. "'s not fair for her to be that much faster than m-"  
  
Right as the saint was about to throw a little fit, as evident by her arms raising into the air, fists curled up and prepared to strike the ground in frustration, she noticed that her legs felt... strangely warm. Like, way warmer than they should. Almost as if she had... no, she couldn't have.  
  
"I didn't... I couldn't have... Jeanne doesn't pee her pants...!" The ruler shouted aloud in the midst of the fog as she rolled onto her back and looked down at her skirt, her irises shrinking in shock once she pulled the fabric aside...  
  
Her panties were drenched. Not just drenched, they were absolutely soaked in the dirty liquid. Not even an inch had avoided the fate of being yellowed by the liquid waste, and as such they felt heavy and disgustingly warm... And yet, while a normal adult would just feel incredibly embarrassed at this accident, Jeanne wasn't exactly an adult mentally anymore, despite her claims to the contrary.  
  
"Ew, ew ew ew ew!" The little minded saint cried out as she tried to get up and onto her feet so she could escape the fog and get home and get changed, but her legs were failing her. Tiring herself out by swinging around that big flag had cost her any chance of getting away with some sense of adulthood intact. Especially once she started hearing a familiar giggle from within the fog, once her head slumped against the pavement.  
  
"Aw, looks like Mommy's not a Mommy after all. She's a little kid like Jack!" The scarred girl chuckled as she stepped out, standing with her legs spread out so that Jeanne's head was right between her feet. "You had such a big accident too, even Jack doesn't wet herself that much. Maybe 'Kiddy Ruler's more of a baby than a kid!" That infernally cheery giggle was getting on Jeanne's nerves, and it would've done so even if she hadn't been practically forced to act like a kid!  
  
"Stop! I'm bigger than you, you're supposed to be nice to bigger people!" Jeanne shouted up at her tormentor, before trying to swipe at the Assassin class servant's thighs, to try and get some sort of control back.  
  
This was quickly stopped by Jack merely tapping Jeanne's shoulders with her tippy toes, causing another few kiddy souls to travel into her body... which caused the blonde to look ever dizzy. "Awwww, looks like Baby's all confused. Let's see if she really is a big girl, once she has Jack's butt on her face~"  
  
"Whaaa... Wait, don't sitty on Jeannie!" The saint cried out in an even more childish manner, if anymore of the souls that made up Jack's existence went into her body, she'd no doubt develop an adorable lisp that would make it utterly impossible for anybody in the war to take her seriously...  
  
And yet, Jack continued to ignore her pleas and cries as she sat straight down on that cute little-fied saint's face. She didn't even have a plan to do anything else but sit on her face, except maybe make her cry uncle to try and let her get free. The only reason she sat down was to continue teasing the regressing saint, and like the kid she was, she had no idea that she set another chain of events in motion.  
  
"Mmmphhh! Jhackieh! Ghet Ohfffffff!" Jeanne shouted from underneath the panty-clad butt that was now sitting atop of her nose and lips muffling her every word, her reddened cheeks turning blue as she started running out of air. Her breathing and tantrum throwing cries slowed down, and her eyes started to dim... until...  
  
A soft sound, almost like the wind being taken out of an instrument, whizzed out of Jeanne's own pissy-panty covered bottom. "Ehehehe..." The saint giggled just softly enough for it to end up sounding normal despite the panty above her covering her mouth, as she started to instinctively push down on her bowels. She had felt the need to relieve herself, and in her current lucidity-lacking state, she was unable to do anything except for obey her body.  
  
With the force comparable to that of toothpaste being rolled out of the tip of the tube, a small serpentine log of poopy just slid its way out of Jeanne's butt, right into the soggy formerly-white underwear that she had the misfortune to still be wearing. And while she grunted ever slightly to try and get it all out, her expression was one of pure bliss. It was as if being forcefully deprived of air by way of a loli-butt was more than enough to short circuit the rest of her adult brain. All that was left was a slightly bigger version of Jack, in a broad sense.  
  
"Eeeeew! Baby made a big stinky in her panties... Well, Jack guesses Jack was right! Eheheheheheh!" That annoying laugh sounded much nicer now that Jeanne's brain had been completely fried, even after the Assassin got off her face and lightly slapped both of her cheeks. "Baby stays right here, Jack'll be right back!"  
  
Jeanne's eyes followed her fellow kid's movements, laughing a little as she got some affectionate cheek slaps. "Okie...!" She chimed as the albino girl took off, letting the 'smaller' girl lift herself up and onto her butt... letting all of that messy mush get squished around on her butt. It wasn't bad enough that it had gotten all wet from the pee, now it was dirty and stinky too! Yet it didn't seem to bother the former saint at all. Even as she started to suckle on her finger out of feeling a need to fill her mouth with something that she could play with.  
  
Fortunately, Jack didn't take that long to get back to her, breaking through the fog in record time. "Here, Baby! Look what Jack got for us!" The albino girl was cheery with her smile curving upward from one end to the other. The reason why she was so happy was obvious once Jeanne looked at what was wrapped around Jack's waist... a big, poofy white diapie! And under her arm were many more, plus a lot of that stuff adults use to make sure babies don't get rashes!   
  
The saint giggled before being kissed on her cheek and gently pushed a little, so that her head would lie back against the ground. "Okay, Baby. Jack'll play Mommy for a bit, you just sit still, okay?" That remark was quickly followed by Jeanne nodding her head rapidly, and before long, her thoroughly used undies were discarded onto another part of the empty and foggy street.  
  
With the same sort of swiftness she used to ruin Jeanne's mind during that little impromptu game of tag, the saint was wiped clean in every spot, to the point where you couldn't even smell a little bit of poopy in the air. Next came the baby powder, which was spread onto Jeanne with such intensity that a small cloud of the stuff got kicked up, joining in with the fog that still filled the street.  
  
Lastly but not leastly, the diaper. While the ruler baby still looked like a giggly deer in the headlights, Jack could easily slide the butt of the diaper underneath her bottom, and wrap the middle through the gap between her thighs before shutting the wings together. Such a nice and disposable infantile garment was the perfect thing for the regressed girl to wear. Jeanne's ticklish giggles as she wiggled her legs back and forth certain made that clear.  
  
"Aaaaand... Done! That's one little Baby all padded up and ready to play!" Jack certainly sounded very proud of the work she did as a 'Mommy', the young white haired girl giggling to herself as she started tickling her regressed friend, triggering a matching childish giggle from the bigger-breasted 'infant'.   
  
"You're so adorable, Baby! Mommy'd be happy to see us both if she could, but she doesn't let Jack take home any strangers..." The Assassin trailed off as she started to redirect her hands so that they prodded up against Jeanne's breasts, giving them a few pokes. "Especially if that stranger's a silly Baby with big Mommy boobies! You look so silly, Baby, and you don't even know it!"  
  
Jack was right, the former French Saint didn't know that she looked silly. The mishmash of souls that now inhabited her body were far too childish to realize that it was even close to being a little strange.  They didn't even mind joining in with their fellow baby friend, resulting in Jeanne pulling her hands up to her impressive bust and digging her hands into both breasts with no real restraint.  
  
In the instant where the blonde girl squeezed into her own still-covered breasts, she immediately let out a rather indecent sounding moan as her nipples started to squirt milk. It seemed like having that many 'children' inside of her had caused her body to have an adverse reaction, resulting in her breasts producing milk despite the fact that she had never been pregnant before.  
  
The droplets that squirted out through the dark-blue cloth was something to behold, especially considering the formerly holy woman that the milk was coming from. It was a sight that thoroughly captivated the younger-looking girl in front of her. Just a few mere droplets of maternal white liquid squeezing their way through the wet cloth was enough to make Jack's eyes home in on her breasts.  
  
Before Jeanne had time to properly register what was happening, she had to let out yet another moan as the eager little Assassin found herself climbing onto the larger girl's lap. She needed to get closer to that untapped source of nutrition. It looked so tasty, so absolutely divine, so irresistibly alluring to a young girl like her.   
  
Once her little padded butt was snugly situated on her fellow baby's lap, she used her nimble fingers to pry away the cloth that had gotten in the way of those lovely breasts, before latching her lips onto the leaky and pink nipple in front of her. It took nary a second before she had begun to suckle like a needy little girl, natural given the kind of girl she was at heart.  
  
Jeanne couldn't understand what was going on, having been thrown too many years back mentally to properly link things together. Her breasts were milky like a Mommy's, but she wasn't a Mommy. Jack was feeding on them like a Mommy's baby should though... so was she a Mommy after all?  
  
All that thinking made the blonde girl rub her head in frustration. It was all too weird and too complex for a girl like her, so instead she just wrapped her arms around the breastfeeding girl, panting and moaning softly as she started to instinctively thrust her hips forward. She wanted something to play with down there as her puss-puss started to grow damp and needy... even though her diaper was in the way. Her childish little mind wanted release, not knowing how to articulate it.  
  
Release would come however, as somehow Jack noticed that her friend was needy, and thus she shifted herself slightly so that their legs were interlocked... which meant that their diapers were now rubbing up against one another. Of course, the Assassin only did so instinctively because she wanted more milk, and that mean that she had to make the younger-minded saint climax.  
  
The more the white-haired girl rubbed her legs and nappy-clad crotch up against Jeanne's, the more the saint returned her forward hip-thrusts in turn. Their pleasures were feeding into one another, as their cheeks reddened and the flow of milk intensified. It tasted so good that Jack eventually just kept humping up against her friend with wild abandon, sending them both spiraling towards the edge of their climax. Right until...  
  
Both girls' eyes shot open as they both arched their backs backward, gasping and screaming in pleasure as they reached a synchronous climax, despite the layers of padding that would've otherwise made it incredibly hard to experience even a little bit of pleasure. Something about how in synch the two young-minded girls were made it possible to cum with all of this infantile fluff in the way...  
  
Their mutual giggling as the soggy fronts of their diapers suddenly turned a little yellow made it all too clear that they hadn't just been able to reach a pleasure-related release. They had let everything come out. Everything that they still had built up within their bladder had come out with their feminine love juices.  
  
The soft brassy sounds from their rears followed up on that thought, as the backs of their diapers sagged down just a little bit. Their bowels had released their contents as well, leaving them both wearing a couple of thoroughly soaked and soiled pampers. A good look for two naughty babies that just came together like a pair of immature lovers.   
  
Once the afterglow started to taper off, Jack suddenly shook to life and leapt off her friend's lap looking more panicked than ever. "Oh no, oh no! Mommy's going to be so mad at me for not being home!" The little assassin jittered back and forth, her messy diaper sloshing from side to side as it reminded her of what had just happened as well. "And she'll be EXTRA mad that I made an oopsie while out, oh dear, oh no... M-Maybe she'll let me get a change if I tell her I dealt with another Baby...!"  
  
Jeanne blinked as the fog in the area started to disappear, giggling a little as she watched Jack stumble back and forth like a worrywart. She didn't know why she was so worried, but it made her laugh. That infantile mishmash of souls that inhabited her body had now assumed complete control of her forever after, so the fact she was a messy butt didn't bother her at all.  
  
The moment the blonde looked around to try and find her blanket of a flag however, Jack was suddenly gone. "Huhh..?" The baby-minded woman scratched the back of her head as she slowly got onto her feet, peering around on the street to find her fellow mud butt of a friend.   
  
She didn't find the Assassin that had turned her into this embarrassing mockery of herself, but she did find her blankie! The Baby-class servant waddled right towards the discarded flag, picking up the cloth and stuffing it into her mouth. Suckling on that important part of her history made her feel all safe, so it would keep her mind occupied as she tried to find her way back to... wherever she was going to go.  
  
The little-minded saint squished her thighs together and started to giggle a little, the sounds muffled by the flag in her mouth. If she didn't know where to go, she'd just have to find a Mommy. Maybe Jack would know where to find one.  
  
With that thought doing its best to stay firm in her mind, Jeanne started to waddle down the street, dragging the pole of her flag along as she continued to teeth into the fabric. Despite how heavy the pole looked, she was managing to drag it along with the power of her mouth alone... which just served to make her look that much more infantile in comparison.  
  
If her past self saw her now, or if her adult mind managed to separate itself from the childish mishmash that was the souls that Jack had forced into her? She'd no doubt be horrified at how she was acting right now. At the same time though, with how nice it felt to be treated just like another girl by the young Assassin, maybe she'd want to experience a little more of this.   
  
With a Mommy nearby to make sure everything was going to be alright...

**Author's Note:**

> A commission by LangHTZK on Deviantart that got a little meat added to it before I released it! Always fun to get back to the diapered Servants.


End file.
